For example, in a digital filter, a hold circuit keeps an input data in time series and the data is multiplied by a multiplier and integration is performed. Data once kept is successively transferred to the following hold circuit and input into another multiplier.
Conventionally, in a digital filter, hold and transferred data are digital data, and a little level down can be omitted. On the other hand, in computers whose main body is an analog operation, it is necessary to treat an analog data, and hold error can not omitted. However, any hold circuit considering about transferring of hold of an analog data is not known.